It is known to provide a wheelchair with drive to each of its four wheels. Such vehicles are conventionally steered by the skid steer principle or by providing that some or all of the wheels are steered by a positive steering mechanism. The skid steer principle provides a high degree of manoeuvrability to a four wheel drive vehicle and is for this reason used in tractors, armoured personnel carriers and the like. This system is not satisfactory for wheelchairs which are likely to be used indoors as the skid steering of the wheelchair would damage flooring surfaces such as carpets. The provision of positive steering mechanisms on wheelchairs adds to the weight, complexity and cost of wheelchairs. The present invention is directed to a four wheel drive vehicle incorporating an alternative steering mechanism.